package cn.turing.firecontrol.server.util;

import javax.crypto.Cipher;
import java.math.BigInteger;
import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.NoSuchAlgorithmException;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.RSAPrivateKeySpec;
import java.security.spec.RSAPublicKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.HashMap;
  
public class RSAUtils {  
  
    /** 
     * 生成公钥和私钥 
     * @throws NoSuchAlgorithmException  
     * 
     */  
    public static HashMap<String, Object> getKeys() throws NoSuchAlgorithmException{  
        HashMap<String, Object> map = new HashMap<String, Object>();  
        KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance("RSA");  
        keyPairGen.initialize(1024);  
        KeyPair keyPair = keyPairGen.generateKeyPair();  
        RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();  
        RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();  
        map.put("public", publicKey);  
        map.put("private", privateKey);  
        return map;  
    }  
    /** 
     * 使用模和指数生成RSA公钥 
     * 注意：【此代码用了默认补位方式，为RSA/None/PKCS1Padding，不同JDK默认的补位方式可能不同，如Android默认是RSA 
     * /None/NoPadding】 
     *  
     * @param modulus 
     *            模 
     * @param exponent 
     *            指数 
     * @return 
     */  
    public static RSAPublicKey getPublicKey(String modulus, String exponent) {  
        try {  
            BigInteger b1 = new BigInteger(modulus);  
            BigInteger b2 = new BigInteger(exponent);  
            KeyFactory keyFactory = KeyFactory.getInstance("RSA");  
            RSAPublicKeySpec keySpec = new RSAPublicKeySpec(b1, b2);  
            return (RSAPublicKey) keyFactory.generatePublic(keySpec);  
        } catch (Exception e) {  
            e.printStackTrace();  
            return null;  
        }  
    }  
    public static RSAPublicKey restorePublicKey(byte [] pubKeyBytes) {  
        try {  
          X509EncodedKeySpec keySpec = new X509EncodedKeySpec(pubKeyBytes);
          KeyFactory keyFactory = KeyFactory.getInstance("RSA");
          RSAPublicKey publicKey = (RSAPublicKey)keyFactory.generatePublic(keySpec);
          return publicKey;
        } catch (Exception e) {  
            e.printStackTrace();  
            return null;  
        }  
    } 
    
    public static RSAPrivateKey restorePrivateKey(byte [] priKeyBytes) {  
        try {  
        	PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(priKeyBytes);
        	KeyFactory keyFactory = KeyFactory.getInstance("RSA");
        	RSAPrivateKey privateKey = (RSAPrivateKey)keyFactory.generatePrivate(keySpec);
        	return privateKey;
        } catch (Exception e) {  
            e.printStackTrace();  
            return null;  
        }  
    }  
    /** 
     * 使用模和指数生成RSA私钥 
     * 注意：【此代码用了默认补位方式，为RSA/None/PKCS1Padding，不同JDK默认的补位方式可能不同，如Android默认是RSA 
     * /None/NoPadding】 
     *  
     * @param modulus 
     *            模 
     * @param exponent 
     *            指数 
     * @return 
     */  
    public static RSAPrivateKey getPrivateKey(String modulus, String exponent) {  
        try {  
            BigInteger b1 = new BigInteger(modulus);  
            BigInteger b2 = new BigInteger(exponent);  
            KeyFactory keyFactory = KeyFactory.getInstance("RSA");  
            RSAPrivateKeySpec keySpec = new RSAPrivateKeySpec(b1, b2);  
            return (RSAPrivateKey) keyFactory.generatePrivate(keySpec);  
        } catch (Exception e) {  
            e.printStackTrace();  
            return null;  
        }  
    }  
  
    /** 
     * 公钥加密 
     *  
     * @param data 
     * @param publicKey 
     * @return 
     * @throws Exception 
     */  
    public static String encryptByPublicKey(String data, RSAPublicKey publicKey)  
            throws Exception {  
        Cipher cipher = Cipher.getInstance("RSA");  
        cipher.init(Cipher.ENCRYPT_MODE, publicKey);  
        // 模长  
        int key_len = publicKey.getModulus().bitLength() / 8;  
        // 加密数据长度 <= 模长-11  
        String[] datas = splitString(data, key_len - 11);  
        String mi = "";  
        //如果明文长度大于模长-11则要分组加密  
	        for (String s : datas) {  
	            mi += bcd2Str(cipher.doFinal(s.getBytes()));  
	        }  
	        return mi;  
	    }  
	  
	    /** 
	     * 私钥解密 
	     *  
	     * @param data 
	     * @param privateKey 
	     * @return 
	     * @throws Exception 
	     */  
	    public static String decryptByPrivateKey(String data, RSAPrivateKey privateKey)  
	            throws Exception {  
	        Cipher cipher = Cipher.getInstance("RSA");  
	        cipher.init(Cipher.DECRYPT_MODE, privateKey);  
	        //模长  
	        int key_len = privateKey.getModulus().bitLength() / 8;  
	        byte[] bytes = data.getBytes();  
	        byte[] bcd = ASCII_To_BCD(bytes, bytes.length);  
	        System.err.println("BCDLength:"+bcd.length);  
	        //如果密文长度大于模长则要分组解密  
	        String ming = "";  
	        byte[][] arrays = splitArray(bcd, key_len);  
	        for(byte[] arr : arrays){  
	            ming += new String(cipher.doFinal(arr));  
	        }  
	        return ming;  
	    }  
	    /** 
	     * ASCII码转BCD码 
	     *  
	     */  
	    public static byte[] ASCII_To_BCD(byte[] ascii, int asc_len) {  
	        byte[] bcd = new byte[asc_len / 2];  
	        int j = 0;  
	        for (int i = 0; i < (asc_len + 1) / 2; i++) {  
	            bcd[i] = asc_to_bcd(ascii[j++]);  
	            bcd[i] = (byte) (((j >= asc_len) ? 0x00 : asc_to_bcd(ascii[j++])) + (bcd[i] << 4));  
	        }  
	        return bcd;  
	    }  
	    public static byte asc_to_bcd(byte asc) {  
	        byte bcd;  
	  
	        if ((asc >= '0') && (asc <= '9')) {
                bcd = (byte) (asc - '0');
            } else if ((asc >= 'A') && (asc <= 'F')) {
                bcd = (byte) (asc - 'A' + 10);
            } else if ((asc >= 'a') && (asc <= 'f')) {
                bcd = (byte) (asc - 'a' + 10);
            } else {
                bcd = (byte) (asc - 48);
            }
	        return bcd;  
	    }  
	    /** 
	     * BCD转字符串 
	     */  
	    public static String bcd2Str(byte[] bytes) {  
	        char temp[] = new char[bytes.length * 2], val;  
	  
	        for (int i = 0; i < bytes.length; i++) {  
	            val = (char) (((bytes[i] & 0xf0) >> 4) & 0x0f);  
	            temp[i * 2] = (char) (val > 9 ? val + 'A' - 10 : val + '0');  
	  
	            val = (char) (bytes[i] & 0x0f);  
	            temp[i * 2 + 1] = (char) (val > 9 ? val + 'A' - 10 : val + '0');  
	        }  
	        return new String(temp);  
	    }  
	    /** 
	     * 拆分字符串 
	     */  
	    public static String[] splitString(String string, int len) {  
	        int x = string.length() / len;  
	        int y = string.length() % len;  
	        int z = 0;  
	        if (y != 0) {  
	            z = 1;  
	        }  
	        String[] strings = new String[x + z];  
	        String str = "";  
	        for (int i=0; i<x+z; i++) {  
	            if (i==x+z-1 && y!=0) {  
	                str = string.substring(i*len, i*len+y);  
	            }else{  
	                str = string.substring(i*len, i*len+len);  
	            }  
	            strings[i] = str;  
	        }  
	        return strings;  
	    }  
	    /** 
	     *拆分数组  
	     */  
	    public static byte[][] splitArray(byte[] data,int len){  
	        int x = data.length / len;  
	        int y = data.length % len;  
	        int z = 0;  
	        if(y!=0){  
	            z = 1;  
	        }  
	        byte[][] arrays = new byte[x+z][];  
	        byte[] arr;  
	        for(int i=0; i<x+z; i++){  
	            arr = new byte[len];  
	            if(i==x+z-1 && y!=0){  
	                System.arraycopy(data, i*len, arr, 0, y);  
	            }else{  
	                System.arraycopy(data, i*len, arr, 0, len);  
	            }  
	            arrays[i] = arr;  
	        }  
	        return arrays;  
	    }  
	}
